Electric signaling apparatus



(No Model.) 2 Shets-Sheet 1.

T. D. LOGKWOOD.

ELEGTRIG SIGNALING APPARATUS. No. 249,147. Patented Nov. 1,1.881.

(No Model.) I 2 Sheets-Sheet 2.

T. D. LOOKWOOD.

ELECTRIC SIGNALING APPARATUS.

No. 249,147. Patented Nov. 1,1881.

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. 72.08.23 Z/MA/WLMZ w. SM M UNITED STATES PATENT OFFICE.

THOMAS D. LOOKWOOD, OF MALDEN, MASSACHUSETTS.

ELECTRIC SIGNALING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 249,147, dated November 1, 1 881.

Application filed May 25, 1881.

To all whom it may concern Be it known that I, THOMAS D. LOOKWOOD, a citizen of the United States, of Maiden, in the county of Middlesex and State of Massachusetts, have invented certain Improvements in Electric Signaling, of which the following is a specification.

My invention relates to an improved method of and apparatus for signaling upon telephone or telegraphic lines in cases where it is necessary to place a number of stations upon the same line or circuit.

It relates particularly to that class of electrical signals wherein the signaling device at each station is included in a branch or local circuit, which at an arranged interval of time from the commencement of the operation is included in the circuit of the main line, or operated by the currents passing in said mainline circuit, the interval of time differing for each station on the line.

The object of my invention is to enable the operator at the central or principal station of such a line to sound a call or alarm at any particular station required without putting in operation any of the others upon the line, and to effect this result in a simple, effectual, and reliable manner.

To this end my invention consists in a novel method of operating from thecentral station the several mechanisms at the various stations, in order that the signal may be given at any particular station; and in certain novel combinations ofapparatus at each station, including the ceiitral station, whereby the required effect is attained.

My invention is has ed upon the fact that when the soft-iron cores of an electro-magnet are attracted to the respective poles of a permanent magnet and an armature placed near to those cores is provided with a strong spring, tending to draw it away, and that it' the inherent magnetism of the permanent magnet is sufficient to overpower the spring, the armature will be held down to the cores as long as no current passes through the coils, or when a current passes whose polarity is the same as the polarity of the permanent magnet; but when a current passes through the coil whose polarity is opposite to that of the permanent magnet the magnetism is thereby weakened (N0 model.)

or neutralized, and the armature is by the force of the spring drawn away.

The subject-matter claimed as new will be specifically designated in the several claims at the end of this specification.

In the accompanying drawings, Figure l is a diagrammatic representation of an electric circuit fitted at each station with my apparatus, and showing the essential features of said apparatus, both at the centraland sub stations. Fig. 2 is a modification of the application of my invention, showing the signaling-instrument included in a branch circuit to earth. Fig. 3 is a second modification, showing how the apparatus is applied to close a local circuit; and Fig. 4 is a detail of the form of magnet employed.

In the drawings I have represented at the central office, in addition to the transmitting devices, a revolving apparatus and bell similarin every respect to those also shown as located at each sub-station. This is done that the operator, by watching the movements of the dial and index-hand of his own apparatus, may intelligently control the movements of the apparatus at each station. I therefore call the bell at the central station No. 1, the bell of the first sub-station No. 2, the second No. 3, and so on until the end of the circuit is reached. I have shown the bell of No. 5 as being in its position of action, and the dials at the central station and at No. 2 as consequently presenting the figure 5 to the index-finger f at the top of the dial. The other stations are provided with similar dials; but for convenience of illustration those of stations 1 and 2 only are represented.

Referring for the present to Fig. 1, A is a side view of a permanent horseshoe-magnet, which is shown in front view in Fig. 4.. It is provided with soft-iron pole-pieces or cores P, which are preferably attached by passing a metal pin or bolt through the end of the permanent magnet and pole-piece. Surrounding each soft-iron core is placed a coil of insulated wire, a, which is included in the line-circuit and forms a part of the main line.

It will be hereafter understood that the term magnet, when used herein, includes the combination of permanent magnet, soft-iron polepieces, and coil.

Eachmagnetisfittedwith,andbyitsinherent attractive power tends to draw down toits polepieces, asoft-iron armature, B, fixed to an armature-lever, I. This lever is pivoted at the center 0, and at its outer end has a lug, c, which turns upward and serves normally to detain in any required position the metallic escapement or circuit wheel i, which is permanently fixed on the arbor II, and when released is rotated by any ordinary system of clock-work, which, forming no part of my invention, I have not considered necessary to describe.

Depending from an adjusting-screw, s, is a strong spiral spring, I), which is fastened to the armature and exerts thereon a constant i'orce, tending to draw it away from the magnet. The magnet and spring at each station are so adjusted in relation to one another that the force exerted on the armature B by the spring bis slightly less than the attractive force exerted by the magnet Athat is, the two forces are so nearly balanced, but prepouderating slightly in favor of the magnet, that the armature, while normally resting at or near the cores of the magnet, will yield to the force exerted by the spring, if that force is increased, even in a small degree, or it the opposing attractive influence ot' the magnet be in a small degree diminished. The tension of the spring I) can be adjusted by turning the screw 8, and the magnet can be adjusted very delicately by means of the device shown in Fig. 4, where the magnetic strength in the cores is regulated by means of a cross-piece of iron, (1, which is placed across the legs otthe permanent magnet, and which can be moved up and down and fastened at any desired point by the screww. The nearer it is placed to the end of the magnet the less will be the magnetic efi'ect upon the soft-iron cores inside the coil. A set-screw, O, limits the upward move ment of the armatm'e-lever.

The escapement-wheel i of each apparatus in the circuit is furnished with square teeth, corresponding in number to the stations 011 the circuit. These are placed at a, suitable distance apart on the periphery of the circuit or escapement wheels, and in each case one tooth,j, of the series is composed of non-coir ducting material, which is inserted into the substance of the metal escapement-wheel i.'

This non-conducting toothj is, of course, differently placed at each station in. the circuit, as shown in the drawings, where the centralofiice wheel has its insulating-tooth placed as the first tooth of the series. In station No. 2 it is the second tooth, and so on. The material ot'-which this tooth is formed also extends forward for a short distance toward the base of the tooth in advance, so that when the lug e of the lever Z strikes the insulating-tooth in any instrument it shall not touch the metallic part of the wheel at any point. This is essential for a reason which will hereinafter appear. Each circuit or escapement wheel is also provided with an extra tooth, a, set at a distance from any of the others, and when the circuit, with its several apparatuses, is not being used, the lug e of each lever will be elevated and rest against the tooth u. This tooth u ati'ords a convenient point at which each wheel may come to rest, so that after each revolution all the wheels shall be in unison with one another, and that at the commencement of a second revolution the tooth a shall be the initial point from which all the wheels start.

Fixed upon the axis h of the escapemeutwheel i is an indicating-dial, g, which is numbered, and which revolves with the wheel and shows when the line is in use, and also which station is using the line, by presenting the number of such station to the index-finger n, which in each instrument is fixed at the top of the ringf, surrounding the dial. It is obvious that when the line is at rest the pointer or index-finger n will be opposite the figure 1.

D is a vibrating bell connected in a branch or shunt. circuit around the escapcment-wheel, the magnet of which must be of sutticiently high resistance to preclude a sutlicicut amount ofcnrrent passing through its coil to vibrate its armature and bell-hammer, except when the shunt on short circuit through the wheel is broken.

k k are ordinary reversing circuit-closing keys, connected respectively to the line and ground. The back contact or bridge, 3 is connected with one poleofbattery II- The frontcontact or anvil, y, of key It is connected with the opposite pole of the battery, and the front contact or anvil, 3 of key It" with an intermediate plate, so as to divide the battery. \Vhen k is depressed the entire battery-cnrrentot' given polarity is transmitted to line. When k is depressed a portion only of the battery is connected, and a much weaker current of opposite polarity is sent to line. The keys, when not being operated, form, by their metallic back contact or bridge. y. the continuation of the line to the ground. The line-circuit commencing at the ground G is through the keys to the coil of the magnet. After leaving the coil it is connected through the metallic supports. or in any suitable manner, to the armature-lever 1, and from thence divides at the point 6, the main line being through the lug e of the lever l to the metal escapement-wheel i; thence through the frame of the instrument to wire 4 and out to the next station. The branch or shunt-circuit line, diverging at point 6, leads to the vibrating bell, after which it is led by the wire 3 to the main wire 7, from thence out to the next station, where the connections are made in the same manner, and at the end of the circuitthe lineis, as usual, connected to the ground G. A short conducting-wire, z, is led from the limit-screw G to the outer binding-screw of the vibrating bell D. In the normal condition of the line all the armatures B are attracted by the magnets A, and the lugs e, engaging with the unison-tooth u of the escapementwheels, prevent their revolution. All the signaling-bells are thus cutout or short-circuited by the route of low resistance through the armature-lever Z and escapement-wheel z, thence passing to the metallic frame, and out by wire 4, and the zero-mark of each dial will be opposite the needle or index-finger a.

The operation ofthe apparatus will be readily understood with little additional explanation. Suppose, for example, the operator at the central station wishes to signal station No. 5, as represented in the drawings. He presses the key It once and holds it down. This connects a portion of the battery, thus sending to the line a weak current of a polarity in opposition to the polarity of the permanent magnets at each station on the line. The magnetism of each magnet A is thus weakened or neutralized, and-is no longer able to hold the armature B against the retractile force of the spring I), which immediately. draws each armature upward with considerable power. This movement is communicated to the lever I, which has its center of motion at 6, and correspondingly depresses its outer end, disengaging the lugs c, and allowing each escapement-wheel to rotate under the influence of its motive power in the direction of the arrow. The wheels at each station work synchronously with one another, and when the operator at the transmittingstation observes by his own dial 9 that the figure 5 has rotated until it is opposite to the index-finger or pointer 12 he releases his key The armatures B will then yield to the influence of the permanent magnets, which are no longer neutralized by an opposing current, and be attracted to the cores, thus elevating the outer end of the lever l, and engaging by its lug e the fifth tooth of each escapement-wheel on the circuit. The circuit will then be substantially in its normal condition, except that each wheelwill have advanced toits fifth tooth, and that the fifth instrument in the circuit has, owing to the fact of its fifth tooth being made of non-conducting material, broken the short circuit round its bell, and the fifth bell is thus included in the main line. The operator then p'resses his other key, is, which, connectingthe entire battery, sends to line a strong current of apolarity agreeing with the polarity of the several permanent magnets. This, of necessity, passing through the magnets of the vibrating bell D of the fifth station, rings it loudly, none of the other bells ringing, because no other is in circuit, and none of the armatures B moving,becausethe magnetism of each permanent magnet is strengthened,instead of weakened, by the passing current, which now agrees in polarity with the polarity of the magnet.

'To prevent any of the bells ringing while the armatures are retracted and the wheels revolving, the short circuit being thus broken, the branch wire 2 is led from the back limitthe vibrating bells, thus forming a second short circuit while the revolution ofthe wheel is in progress. The material of the insulating-tooth j, as previously stated, is also extended for a short distance in advance on the periphery of the wheel, as seen in No. 5, so that all danger of contact between the lug e and the metallic substance of the circuit-wheel shall be prevented and the current confined to the bell desired to be rung.

The bell-hammer may be vibrated either by an absolute make and break of the circuit or by an auxiliary shunting device, which alternately includes in and excludes its own magnet from the circuit.

The modification shown in Fig.2 is operated in substantially the same manner, but the circuits are differently arranged, and the details of the apparatus are also slightly different. In Fig. 2, which illustrates this modification, I have represented the apparatus of one station on a circuit fitted with my apparatus. This apparatus differs from that before described only in that the escapement-wheel i is entirely made of some insulating material, such as hard rubber, with the exception of the tooth corresponding to the number of the station. This tooth is a conductor, and is in metallic connection with the metallic axis or arbor of the wheel, and thus, through the frame-work of the apparatus, to the bell D. Entering from the left and proceeding in the direction of the arrow, the main circuit is through the switch Z to the coils of the magnet Aand out toward the right. A short wire connects the main line, after it leaves the magnet-coil, to the armature-lever l, and there normally ends; but when the circuit is operated in the beforedescribed manner the escapement-wheel t, in common with the other wheels on the circuit, rotates until the number of the station desired is opposite the index, where it stops by the reengagement of the lug ewith the wheel, by.

which engagement the branch circuit is also completed through the conducting-tooth and axis of the non-conducting wheel, and through the bell D to earth, cutting off temporarily the remainder of the main circuit. In this case, between the last magnet-coil on the circuit and the terminal ground, must be inserted a resistance greater than that of the coil. I have also shown the transmitting-keys and battery in this drawing, and by connecting them in the manner delineated at each station on the line I may, if I so prefer, give any or all of the stations the power of individually calling any other station,although Iprefer to give such power to the central station alone. The keys are normally kept out of circuit by the switch Z, which must be thrown off when the keys are to be operated.

The modification shown in Fig. 3.represents IIS those hereinbelore described, and the same bat tery used to operatethe transmittiug-teleph one may be employed to ring the bell.

I do not desire to confine myself to the particular construction and arrangement of circuits herein shown and described, as these may be greatly varied without departing from the principle of myinvention, and many modificacombination of an electromagnetic call-instrutions will readily suggest themselves to persons skilled in the art. I may, forexample, improve the electrical connection between the escapement-wheel and the armature-lever in Fig. 3 1 by fixing on the same axis as the wheel a con- 3 1 helices on its poles, and an armature, and operating to release said escapement-wheel when a current of given direction is on the line-cirducting-disk having an insulated surface at one point ofits periphery corresponding to the insulated tooth on the wheel, and a frictional conducting-spring bearing on said disk.

It is essential, for the proper working ofmy invention, that each consecutive compound permanent magnet A shall be so connected in the l a series of electromagnetic signaling'instrucircuit that their polarity shall at each station be the same, and oppose the polarity ot'current sent when the key is pressed, which connects the smaller amount of battery to line. This is readily done in practice by any person who is ordinarily experienced in the art of tclegraphy; for if, on connecting any station, it be found that when the current from the smaller battery is sent to line,instead of neutralizing the magnet and freeing the armature the magnetism is increased, it is merely necessary to reverse the connecting-wires at such station, which operation will give the required direction ofcurrent.

To connect the magnets properly it would readily become a matter of routine to have the binding-screws of the apparatus so marked that the person connecting the instruments would at once understand that the bindingscrew marked, for example, G must always be connected to the line from the central station, and that the line toward the ground end must always be connected to the screw marked E.

I am aware that signaling-bells have been heretofore opera-ted individually by including them in a shunt-circuit which at the will of the operator is closed or broken by the action of an electromagnetic escapemeut, such a device being shown in Letters Patent granted to S. \V. Francis, No. 219,244, September 2, 1879. I am aware, also, that such bells havealso' been operated by connecting them in. the earth branch, which is connected and disconnected at will. I consequently do not broadly claim any such device; neither do i claim as a new invention the special form of electro-magnet which I employ, as it is old; but

What I do claim is 1. A11 individual signaling apparatus consisting of acompound permanent magnet provided with soft-iron cores, helices forming part of the main-line circuit, an armature and lever, and a retractile spring, in combination with an electromagnetic call-instrument in a shunt, ground branch, or local circuit, a rotary circuit-changer or switch controlled by the compound magnet, and operating to bring said call-instrument into position to sound the alarm, and serving also as an escapementi wheel, and an auxiliary branch circuit, nor- .mally open, but adapted to close and shortcircuit the call-instrument by the action of the f armature-lever during the period of revolution of the rotary switch.

2. In an individual signaling apparatus, the

ment controlled and brought into and out of position to sound the alarm byan escapementwheel which acts as a switch, and the trip-motion comprising a permanent magnet, with cuit, and to engage and detain it when no cur-- rent is upon the line, substantially as described.

3. In an electric circuit, the combination of ments, each normally cutout of circuit, and a series of rotary switches or circuit-changers, acting also as escapement-wheels, and adapted to include anydesired bell in the main circuit, or in position to sound the alarm, each rotary switch being controlled by the armature-lever of acompound permanentmagnet,which,when no current is upon the circuit, engages with and detains the eseapement, the armature being attracted by the permanent magnet, but which, when a currenttraverses theline in direction opposing the polarity of said permanent magnet and neutralizing the same, thus causing the armature to withdraw, releases the escapement and permits the switch to rotate, substantially as and for the purpose set forth.

4. The combination of a circuit-changing armature-lever, l, adapted to break the short circuit round an electromagnetic signalinginstrument and instantly re-establish a short circuit by making contact with the branch wire 2, with the compound permanent magnet A, the signaling-instrument D, the rotary circuit-changer 'i, the shunt-circuit 3, and the branch circuit 2, substantially as described.

5. The combination, in a system of electrical signaling, of the compound magnet consisting of the permanent magnet A, coils a, soft-iron pole-pieces P, armature B, armaturelever l, and retractile spring 8, the signalingkeys k k, the battery L B, the electric escapement i, normally forming part of the main circuit, the bell D, the shunt-circuit including said bell, and the branch circuit 2, substantially as described.

6. The combination,in an individual signaling-instrument, of the compound permanent magnet A, with a rotary switch, adapted also to operate as an escapement, and a signalinginstrument included in local branch or shunt circuit, substantially as and for the purpose tooth, j, in the rotary electric switch i, subset forth. stantiall; as set forth.

7. In an individual signaling-instrument, In testimony whereof I have signed my the combination of the compound permanent name to this specification, in the presence of 5 magnet A with a rotary switch, a, adapted, two subscribing witnesses, this 23d day of 15 also, to operate as an csoapement, and a sig- May, 1881.

naling-instrument in a local branch or shunt THOMAS D. LOOKWOOD. circuit, and adapted to be brought into posi- Witnesses: tion for operation, when desired, by the en- J. B. HENOK, J r.,

10 gagement of the armature-lever l with a given W. G. TOMPKINS. 

